The present invention relates to a box blank holding device in a box-making machine, which device holds blanks while moving them to a predetermined position and, more specifically, to a device of this kind that is capable of securely holding box blanks, already folded by the machine, regardless of the thickness and the hardness or softness of the blanks.
Conventionally, a box blank holding device in a boxmaking machine has a pair of holding members projecting from a main body and adapted to, for example, be moved toward and away from each other by a gear mechanism so that the blanks are released when the holding members are moved away from each other. A means for moving the holding members toward and away from each other is adapted to, for example, move the pair of holding members close to each other until their positions are separated by a predetermined width in accordance with the thickness of the blanks to be held, which blanks may be arranged in a pile.
However, in the arrangement in which the pair of holding members project from the main body, they present obstacles to the feeding of blanks already folded by the box-making machine to the piling-up section of the machine, particularly when the holding members are adapted to hold opposite sides of the blanks. If the space between the pair of holding members is increased in order to overcome this inconvenience, however, the stroke of the holding members during their movement toward each other is increased correspondingly. Such an increase is not desirable from the practical point of view because it leads to a reduction in the efficiency of the work. In addition, because such an increase requires an increase in the length of the main body, the blank piling-up section may become large and, hence, the entire machine may become undesirably long and large.
Further, in the arrangement in which the pair of holding members are moved toward each other by a gear mechanism so as to be separated by a predetermined width, if, for instance, the total thicknesses of the piles of folded blanks varies among the piles, the result will be that a pile having a total thickness greater than the predetermined width will be held under a high pressure, whereas a pile having a total thickness less than the predetermined width will be held with a low pressure. Thus, there is a risk that the blanks in a pile may be damaged or that they may not be held securely. In order to avoid such a risk, it is necessary to adjust the space between the holding members for each pile, thereby adding an operational inconvenience.